Burglar-alarm.



G. A. BREWSTER.

BURGLAR ALARM.

APPLIOATION FILED MAY 17, 1911.

1,065,861 Patented June 24,1913.

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GEORGE A. BREWSTER, OF NEW YORK, N. Y.

BURGLAR-ALARM.

To aZZ whom it may concern Be it known that I, GEORGE A. Bnnwsrnn, acitizen of the United States, and a resident of the city of New York,borough of Brooklyn, in the county of Kings and State of New York, haveinvented a new and Improved Burglar-rilarm, of which the following is afull, clear, and exact description.

Among the principal objects which the present invention has in view isto provide an alarm of the character mentioned adapt ed for temporaryinstallation on the knob of doors and in conjunction with the keys forlocking same.

ith this object in view the invention consists in providing anattachment quickly and readily installed upon a door knob or otherrotary closure device employed for opening doors or windows.

One embodiment of the present invention is disclosed in the structureillustrated in the accompanying drawings, in which like characters ofreference denote corresponding parts in all the views, and in which-Figure 1 is a detail view in front elevation of a door escutcheon plateshowing in conjunction therewith a circuit closing attachmentconstructed and arranged in accordance with the present invention; Fig.2 is a detail view, on an enlarged scale, of the construction shown inFig. 1; Fig. 3 is a cross section taken on the line 4-4 in Fig. 3.

It is the principal purpose of the circuit closing attachment shown inFigs. 1, 2 and 3 of the drawings that the movement of the door knobnecessary to open the door should close the contact and complete theelectric circuit for actuating the bell 19. The attachment is providedwith a clamp which is formed of two side pieces 24, these being bowedintermediate their ends and pivotally connected at 25 each to the other.To insulate the side pieces 24 from the shank 26 of the door knob 27 thesame are covered at and adjacent the bowed portion with rubber tubing28. Loosely passed through a perforation in one of the side pieces 24and thread engaged with the other side piece 24 is a screw 29, bymanipulating the knurled head 30 of which the side pieces 24, 24 aredrawn together, the collar 31 rigidly formed on the screw 29 serving tomove the free side 24 toward the engaged side. Intermediate the sidepieces 24 and encircling the screw 29 is a spiral spring 32, the ofiiceof which is to separate the side pieces 24.

Specification of letters Patent.

Application filed May 17,1911.

Patented June 24, 1913.

Serial No. 627,666.

Fixedly connected with one of the side pieces 24 is a suspension hangingframe 33. The frame 33 is provided with a binding post 34 under thescrew whereof is inserted the end of one of the wire mains 20. Mountedat the end of the frame 33 is a bracket 36. The bracket 36 is shaped asshown in Fig. 3 to form an elliptical loop 37 to surround the pendant38. The bracket 36 has an upturned extension adapted for dispositionparallel with the frame 33 and attachable thereto by means of a screwstud 39, the binding screw 40 serving to hold the wire 21. Interposedbetween the stud 39 and the metallic parts connected therewith and theframe 33 is an insulating block 35.

The pendant 38 is weighted at the lower end to insure the verticalposition of the said pendant, the same being hung on a pivot 41 which isset out from a short bracket 42 fixedly mounted on the frame 33.

iVhen installing the device the side pieces 24 are spread to pass thefree ends over the shank of the door knob. The screw 29 is thenmanipulated to draw the side pieces together, the shank 26 restingbetween the bowed sections of the said pieces. The device is so adjustedthat the pendant 38 hangs substantially at the center of the loop 37. Itwill be seen that if the switch 16 be now closed and the door knob beturned to open the door, the frame 33 and loop of the bracket 36 willswing about the center and the loop 37 be brought in contact with thependant 38. The pendant 38 being electrically in contactwith the frame33, and the frame 33 in electrical contact with the wire 20, the circuitfor actuating the bell 19 is established when the pendant 38 touches theside of the loop 37, and this for the reason that the loop 37 is part ofthe circuit being electrically connected with the wire 21. The loop 37being relatively small it will be seen that before the knob 27 issufficiently turned to release the door the alarm has been sounded. Inthe operation of the device the alarm will cause the interloper tosuspend operations, when the knob 27, resuming its normal position, thependant 38 becomes disengaged from the loop 37. The above describedaction will reoccur should a second attempt be made, thus effecting bythe employment of an alarm of this character a purpose different fromthat usually effected, where the alarm operates once and once only.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is In a burglar alarm, the combination of anelongated frame having at one end thereof aclamp, the jaws whereof areelectrically in sulated; an operating screw for said jaws; an insulatingblock permanently mounted on said frame at the end thereof opposite saidclamp; a closed metal ring bracket rigidly mounted 011 said block; abinding post mounted on said frame in electrical contact therewith; asecond binding post mounted upon said block, having electrical contactwith said bracket, said binding posts being adapted to receive theterminals of a metallic electric circuit; and a metallic endweightedpendulum pivotally mounted on said frame and extending through saidbracket in the closed ring thereof, said pendulum being adapted tomaintain its vertical arrangement when said frame is moved from itsnormal position, and to be engaged by said bracket when said frame is somoved, to thereby complete the electric circuit incorporating saidbinding posts.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

GEORGE A. BREWSTER.

lVitnesses E. F. Mnnooon, J. P. DAVIS.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. G.

